I am building a 50MHz clock by using ABRACON ACOL-50-EK crystal clock oscillator. I have connected 3.3V supply (with a 0.1uF capacitor to ground) to Vdd (pin 14). GND (pin 7) is grounded and output is from OUT (pin 8). I am getting a sine wave and I do not think that would be a good clock signal.
Unfortunately ABRACON has not given any circuits that I could refer to and I got the capacitance hint from another circuit around a different oscillator manufacturer. [Before I connected the 0.1uF capacitance, I was getting ~25KHz oscillation which made me think, may be I got the wrong part – that went on for a while]
I suspect many of you have done this before, so what am I missing ? How is the 15pF output capacitance figure into the design ? How is the 0.1uF calculated ?
Best Answer
If you are using a 100 MHz scope, then a 50 MHz square wave will look like a 50 MHz sine wave as all of the harmonics will be killed (150 MHz, 250 MHz, 350 MHz, etc).